Mine roof support systems

ABSTRACT

A mine roof supporting system in which a plurality of roof supports, each having fluid-operated telescopic props, are arranged at intervals along a mineral face and are advanceable, by hydraulic jacks towards a conveyor, in a desired sequence of advancing operation. The advancing operation is carried out through a pair of pilot lines which are alternately interconnected with a fluid pressure source by a two-position control valve. One pilot line causes the support to advance, and the other causes it to reset. However, each line is isolated from the supports until the signal in the other line deactuates the isolation means. Therefore, each support will not advance until the next preceding support has been reset.

[52] U.S.C1

United States Patent [54] MINE ROOF SUPPORT SYSTEMS 10 Claims, 7 Drawing Eigs.

9l/411, 61/452, 91/1, 91/468 [51] 1nt.Cl ..F15b 11/20, F156 13/07 [50] FieldofSearch 91/1,411', 412, 413, 468; 61/452; 92/5 [56] References Cited UNITED STATES PATENTS 3,202,058 8/1965 Bolton et a1. 61/452 X 3,216,201 11/1965 Kibble et a1 91/1 X 3,217,603 11/1965 Pottset a1. 91/413 X 3,217,606 11/1965 Bolton eta1..... 91/1 X 3,228,300 1/1966 Potts et a1, 91/1 3,272,084 9/1966 Bolton et a1. 61/452 X 3,285,015 11/1966 Carnegieetal 91/1X Primary Examiner-Martin P. Schwadron Assistant Examiner1rwin C. Cohen Attorney-Christensen and Sanbom ABSTRACT: A mine roof supporting system in which a plurality of roof supports, each having fluid-operated telescopic props, are arranged at intervals along a mineral face and are advanceable, by hydraulic jacks towards a conveyor, in a desired sequence of advancing operation. The advancing operation is carried out through a pair of pilot lines which are alternately interconnected with a fluid pressure source by a two-position control valve. One pilot line causes the support to advance, and the other causes it to reset. However, each line is isolated from the supports until the signal in the other line deactuates the isolation means. Therefore, each support will not advance until the next preceding support has been reset.

PATENTEDJUNEQIH?! 3 589 241 sum 2 [1F 5 PROP SET PILOT u/v/r POSITION P/LOT LINE PATENTEU JUN29 I97! SHEET 3 BF 5 NO 7 SEQUENCE VALVE SNAKE VALVE NEXT: Eur ONE 67 SNAKE VALVE 48 SEQUE PATENTEH M29 1921 3; 589,241

SHEET l 0F 5 PATENTEU M129 0?:

SHEET 5 [1F 5 MAIN PRESSURE FLUWMETER 7 MAIN RETURN 6 5 6 S I l l 87 T GAUGE H SEE/$3 E r PRESSURE ggfiggf PANEL a0 76 ADVANCE PILOT 82 SURE f; UN/T ADVANCE POSITION INDICATOR & 69 COUNTER N RE0U0/N0 84 VALVE 2000/1000 PS1 29 ADVANCE -/N0/0Ar0R VALVE LVE 28 TUKLASTM P0SN2. SET lRECT/ON UNIT 50 GAUGE-- PILOT CONTROL PRESSURE VALVE I k 17 40 HYDRAULIC COUNTER MINE ROOF SUPPORT SYSTEMS This application is a continuation of application Ser. No. 678,l 47, filed Oct. 9, i967, and now abandoned.

BACKGROUND OF TH E INVENTION i. Field of the Invention This invention relates to mine roof support systems in which a plurality of mine roof supports are arranged at spaced intervals along a mineral face and are advanced towards the mineral face in a desired sequence during a mineral-cutting operation.

Each mine roof support includes one or more telescopic, hydraulically operated props and is connected to an abutment, for example, a conveyor by a hydraulically operated jack. An advancing operation of a roof support includes the steps of collapsing the props so that they are no longer set against the roof, contracting the jack so as to move the roof support up to the conveyor and then extending the props so that they become reset against the roof.

ii. Description of the Prior Art Roof support systems in mines are known in which the first roof support in the sequence is caused to undergo its advancing operation. When, and only when, that roof support has completed its advancing operation, a signal is automatically sent by and from the first roof support to the second roof support in the sequence, and that second roof support 'is automatically caused to undergo its advancing operation. When the second roof support in the sequence has completed its advancing operation, it automatically sends a signal to the third roof support in the sequence automatically to cause the third roof support to undergo its advancing operation.

With a roof support system of this known type, if circumstances should prevent the full advancing movement of a roof support up to the conveyor (for example, due to debris on the floor between the support and the conveyor or if the support is trapped by a roof which collapses as the props collapse), the sequential advancing operation of the supports stops and the support in question has to be dealt with by sending a man along the coal-face to that support. The sequential advancing operation of the supports cannot be restarted until the man has dealt with that support and that support has finished its advancing operation.

Such a stoppage reduces the total quantity of cut mineral produced in a given period of time.

SUMMARY OF THE INVENTION According to this invention a mine roof support system includes a plurality of advanceable mine roof supports, arranged at intervals along a mineral face, in which the advancing operation of a roof support, after the previous roof support has completed its advancing operation, is initiated by the transmission of a single fluid-pressure signal from a control point, common to all the roof supports, to the roof support which is required to advance.

The invention also provides a mine roof support system including a plurality of advanceable mine roof supports, arranged at intervals along a mineral face, and fluid-pressure pipeline means connected from a source of fluid pressure through a control point, which may be spaced apart from the roof supports, to each of the roof supports, the fluid-pressure pipeline means including normally closed valve means between each roof support (other than the first to operate in the sequence) and the control point, the advancing operation of a,roof support being initiated by the transmission ofa fluidpressure signal from the control point to the support which is required to advance and, during the advance or at the completion of the advance of that roof support, the normally closed valve means between the control point and the next roof support which is to operate in the sequence being put in such a condition that the advance of the next roof support is initiated when the fluid-pressure signal is next transmitted from the control point.

The invention further provides a mine roof support system including a plurality of mine roof supports, arranged at intervals along a mineral face, a fluid pressure supply line and a fluid return line disposed along the mineral face, each roof support having associated with it valve means by which the support is connectable to the fluid pressure supply line and is connectable to the fluid return line, a first pilot fluid line which, when pressurized, actuates the valve means of one of the supports to cause that one support to lower away from the roof and to advance towards the mineral face, a second pilot fluid line which, when pressurized, actuates the valve means of the said one support which has advanced towards the mineral face to cause the said one support to reset against the roof, the control valve means located at a control point and capable, in one position, of pressurizing the first pilot fluid line but not the second pilot fluid line, and, in another position, of pressurizing the second pilot fluid line, the valve means associated with each support being such that, when the first pilot fluid line is pressurized, the said one roof support which lowers and advances is the one which is next in the sequence of operation of the system after that support which has been reset against the roof by pressurizing the second pilot fluid line.

BRIEF DESCRIPTION OF THE DRAWINGS Of the seven accompanying drawings,

FIG. 1 shows a plurality of advanceable roof supports disposed along a coal face,

FIGS. 2A and 2B show parts of one of the roof supports and its associated control valves,

FIGS. 3A and 3B show parts of another of the roof supports and its associated control valves,

FIG. 4 shows the control apparatus at the control point remote from the roof supports, and

FIG. 5 is an instructional drawing showing how the previous FIGS. 2A, 28, 3A, 3B and 4 fit together.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of the drawings, a coal-cutting machine 1 is proceeding from left to right of a coal-face 2, removing material therefrom. The removed material is transported to the left-hand end of the coal-face by a conveyor 3 and the roof of the mine in the region of the coal-face is supported by a plurality of roof supports 4 positioned at equal intervals along the length of the coal-face.

Each roof support is connected through suitable control valve means (to be described later), to a main pressure supply line 5 and to a main return line 6 both of which lines extend from one end of the coal-face to the other and both of which are associated with a source of liquid under pressure 7 located in the so-called stable beyond the left-hand end of the conveyor. Neither of these two lines is shown in FIG. ll, but they are shown in FIG. 2B.

Each roof support has three telescopic hydraulic props 8 which, when connected by the control valve means to the main pressure supply line, extend in height so that the roof support can be set against a roof to support the roof in the region of the support. When the three props are connected to the main return line by the control valve means, the props shorten so that they no longer engage the roof.

Each roof support also has a hydraulic jack 9 connected between it and the conveyor. Each jack can be connected to the main pressure supply line, by the control valve means, so that, when the props of its associated roof support are not set against the roof it can be contracted to move the roof support towards the conveyor.

Each jack can also be connected to the main pressure supply line, by the control valve means, so that when the props of its associated roof support are set against the roof, it can be extended to move that part of the conveyor in front of the roof support away from the roof support.

However, it is not necessary for every jack to perform this function of moving the conveyor. In practice, it is sufficient for, say, every fourth jack along the coal-face to perform this function. The jack of the roof support shown in FIG. 2 is normally employed only to move its roof support up to the conveyor. The jack of the roof support shown in FIG. 3A is, however, normally employed not only to move its roof support up to the conveyor but also to move the conveyor away from the roof support.

Each control valve means includes a main control valve block and a prop release/yield valve block 11. The valve block 10 incorporates four valves, two of which 12 and 13 operate to advance the conveyor away from a roof support, the third of which 14 operates, with valve 13, to move the roof support up towards the conveyor and the fourth of which 15 operates to extend the props and set them against the roof.

Valves 12 and 15 are connected to the main pressure supply line 5 by a branch line 16 and valve 14 is connected (as will be described later) to the main pressure supply line 5 by a pullpressure supply line 17. Each of these valves, and valve 13 are connected, by branch return line 18, to the main return line 6.

Each of the valves 12, 14 and I5 is, as will be explained later, normally operated by the application of a hydraulic pressure signal to their associated plungers I9, 20 and 21.

In the hydraulic circuit associated with each prop 8 there is included a release valve 22 and a relief valve 23. Each release valve 22 is, as will be explained later, operated by the application ofa hydraulic pressure to the piston 24 engaging its movable valve element.

At a control point at the left-hand end of the coal-face is a control equipment by which pressure signals can be applied to the various valves of a roof support, thus affording remote control of the supports.

The control equipment, see FIG. 4, includes a support control valve 25 which is connected by way of an on/off valve 26 to the main pressure supply line 5. In one position of the support control valve 25, which is used to collapse the props and to move the support up to the conveyor, the main pressure supply is connected to a first pilot signal line 27. The pilot signal line 27 is connected to a direction control valve 28.

This direction control valve has two operating positions. In one position it joins the support control valve 25 to the roof support at the left-hand end of the coal-face and when in such position, the roof supports advance one after the other in a direction going from left to right. In the other operating position of the direction control valve, the support control valve is joined to that roof support at the right-hand end of the coalface and, when in such position, the roof supports advance one after the other in the opposite direction-that is to say, in a direction going from right to left.

The connection to the first roof support from the direction control valve 28 and the connection to the last roof support from the direction control valve 28 are the same and only one of them will be described.

The direction control valve 28 is connected by a line 29 to an assembly of four check valves 30, 31, 32 and 33 (see FIG. 2B) which are so connected as to allow the roof support to operate in response either to a pressure signal coming from its left or to a pressure signal coming from its right.

Check valve 30, which opens when pressure is in line 29, is connected to a first sequence valve 34, and with the valve in the position shown in the drawing, is also connected, through the body of valve 34 to a line 35. The line 35 is connected by line 36 to the pistons 24 of the prop release valves 22 and is connected by line 37 to the plunger 20 of valve 14. It is also connected by way of a restrictor 85 to the branch return line 18.

With the valves 26, 25, 28 and 34 in the positions mentioned above, the main supply pressure will open the prop release valves, thereby allowing the props to collapse. Liquid from the props will pass along a line 38 and through the main control valve block 10 to the branch return line 18. Furthermore, the main supply pressure will open valve 14 thereby allowing the main supply pressure in pull-pressure supply line 17 to pass through the valve 14, and a line 39 to one side of the jack 9, causing contraction of the jack with consequent movement of the roof support up to the conveyor.

For the purpose of setting the props against the roof after the roof support has so moved, the support control valve 25 is moved to its other position. In this position the main supply pressure is connected to a second pilot signal line 40. At the same time the line 29 is maintained at a pressure somewhat lower than that at which it was formerly pressurized (for example l,000 pounds per square inch instead of 2,000 pounds per square inch) by means of the reducing valve 41 connected across the support control valve 25 to the first pilot signal 27. This reduced pressure in line 29 holds open the valves 14 and 22, and also a pressure-operated valve 42.

The pilot signal line 40 is connected to the valve 42, and since this valve is open, the pressure in the pilot signal line passes by way of a line 43 to the plunger 21 of valve 15. This opens valve 15 and the main supply from branch line 16 passes through the valve and by way of the line 38 and valves 22 (which, as stated below, are held open) to the props to set them against the roof. The liquid flowing to the props is supplemented to some extent by the liquid in the pilot signal line 40. This liquid flows by way of restrictors 44 a line 45 and a check valve 46 to the line 38.

When the props are set against the roof, pressure builds up in line 38 and closes the check valve 46. Pressure, due to the liquid in the pilot signal line 40, then builds up in the line 45 which is also connected to a piston 47 in valve 34, which piston, when pressurized, causes movement of the movable valve element of valve 34 to prevent communication between the line 29 and the line 35, and to open the line 29 to a line 48. The reduced pressure in the line 29 holds valve 34 in its new position.

The line 48 is connected to a second sequence valve 49 and, as shown in FIG. 28, through the valve body to a line 50. The line 50 is connected to that surface ofa piston 51 remote from the movable valve element of valve 49. Because of the reduced pressure in line 29, and hence in line 50, the piston moves against the movable valve element. However, the force acting on the plunger is not sufficient to overcome the pressure of the spring which biases the movable valve element to the position shown in the drawing.

It will now be appreciated that by moving the support control valve 25 first to one position and then to its second position, the roof support shown in FIGS. 2A and 2B has undergone a complete advancing operation, that is to say, the props have lowered away from the roof, the support has moved towards the conveyor and the props have then been reset against the roof.

In order to cause remote advancing operation of the next roof support in the series, say the one shown in FIGS. 3A and 3B, the support control valve 25 is moved back to its first position. Main pressure is thus applied to the first pilot line 27 and hence to lines 48 and 50. The force now acting on the piston 51 is sufficient to move the movable valve element upwards so as to disconnect the line 48 from the line 50 and to connect the line 48 with a line 52. The movable valve element is held in its new position by the pressure in line 48.

The line 52 is connected to the assembly of four check valves 30, 31, 32 and 33 in such a way as to open valve 33, thus joining the line 52 to a support-joining line 53. This line 53 is connected to an assembly of four check valves of the next roof support 30', 31, 32 and 33', and to a first sequence valve 34'.

The line 53 to the roof support shown in FIG. 3 corresponds to the line 29 to the first roof support and it will be appreciated that, the main pressure in line 53 will cause the props 8 of the support to lower away from the roof and for the jack 9 to move the roof support towards the conveyor.

When this has happened, the support control valve 25 is moved to its second position, to lower the pressure in the first pilot signal and to pressurize the second pilot signal line. The props will then be reset against the roof and the second sequence valve 49' will be put in such a condition, as was the second sequence valve 49, that the first pilot signal line can be connected to the assembly of four check valves of the next roof support to be operated when the support control valve is moved back to its first position.

It will now be appreciated that the advancing operation of each roof support is initiated by a single fluid pressure signal transmitted to the support which it is desired to advance from a control point common to, and in this embodiment remote from, all the supports. It will also be appreciated that the two definite fluid pressure signals from a control valve are necessary, in this embodiment, to cause a support to undergo an advancing operation; the first signal initiating the operation and causing the support to undergo a part of its advancing opcration and the second signal causing the support to undergo the other part (that is to say, the remainder) of its advancing operation.

In a system like that just described, the pressure drop in the lines 29, 53, 53' etc. and the valves connected between them may be such that, after, say five or six roof supports have advanced, efficient operation is difficult.

If this is so, some of the roof supports (say every sixth) may be provided with a modified second sequence valve which can be regarded as a regenerative sequence valve.

The roof suppon shown in FIGS. 3A and 38 has such a modified sequence valve and since this roof support is otherwise identical with that shown in FIGS. 2A and 28, only that valve will be described in detail.

Referring particularly to FIG. 3B, the line 48' from the first sequence valve 34' is connected by a restrictor 54 directly to the piston 51' (in the valve 49 it is connected through the valve body to the piston 51). The purpose of the restrictor 54 is to stop pressure surges in the line 48' jerking the movable valve element of valve 49' away from the position shown in the drawing.

When the pressure in the first signal pilot line 27 is raised from its reduced value to that of the main pressure supply by suitable movement of the support control valve, the piston 51 moves the movable valve element of valve 49 thus connecting lines 80 and 52' together. Line 80 is connected to a line 81 which extends along the coal-face and which is connected to the first pilot signal line 27. Thus the pressure of the first pilot signal passed through the assembly of four check valves to the next support in the series is substantially the same as that which was supplied to the first support to operate that support.

Earlier in the description of this embodiment of the invention it was mentioned that some of the hydraulic jacks 9, 9' etc., say every fourth, performed two functions. One function has already been described in detail namely that of moving the roof support to which it is connected towards the conveyor. lts other function is to advance that part of the conveyor to which it is connected away from the roof support when the props of the roof support are set against the roof.

In order that the hydraulic jack may perform its second function, some of the roof supports, say every sixth, has a snake valve.

A snake valve is shown, for convenience, associated with the roof support of FIGS. 2A and 2B, and comprises a snakevalve body 55 having two similar pressure-operated valves 56 and 57. The pressure-operated valve 57 is employed when the advancing sequence is taking place from the left-hand end of the coal-face to the right-hand end of the coal-face and the pressure-operated valve 56 is employed when the advancing sequence is taking place in the opposite direction.

The operation of the snake valve now to be described, occurs when the advancing sequence is taking place from the left-hand end of the coal-face to the right-hand end of the coal-face.

When pressure from the main pressure supply is present in the first pilot signal line 27 (the support control valve being in its first position) it is also present, as has been described above, in the line 35. The line 35 is connected, by the line 58 to the piston 59 of valve 57 and piston 60 of valve 56. A

tapping line 61 from the line 29 connects the line 29 to the valve 57. Because of the pressure on pistons 59 and 60 of valves 57 and 56 these valves are open. The tapping line 61 is thus connected to valve 63, keeping that valve in a closed position. It is also connected through check valve 64 to line 65 which is connected, not to the next snake valve in the series, but to the next-but-one snake valve in the series.

The pressure in line 65 opens a valve (say 66"), which corresponds to valve 66 shown in FIGS. 2A and 2B, in the nextbut-one snake valve (say 55") opening that valve 66" and connecting the line 65 to a line (say 67") corresponding to the line 67 of FIGS. 2A and 2B. The line 67' is connected to a valve, (say 12"), corresponding with valve 112, on the roof support next after that which has the snake-valve 55". This pressure in the line 67 will open the valve 12" connecting the branch line I6" to the hydraulicjack 9" to advance that part of the conveyor connected to it away from the roof support. If desired the line 67" may be connected to several valves (corresponding to valve 12') for the purpose of operating several jacks.

To enable the operator of the support control valve 25, at the control point, to be aware of the progress of the advancing operation, certain monitoring devices may be included in the system.

One such monitoring device is a hydraulic counting device 68 (see FIG. 4), whose purpose is to count the number of roof supports which have finished their advancing operation.

The hydraulic counting device 68 is associated with line 69 extending from the reduced-pressure side of a reducing valve 82 to a plungeroperated valve 70 on and movable with a roof support. This valve is normally closed by pressure in a line 71 which isjoined to line 36.

During the advancing movement of the roof support, line 36 and hence line 71 is pressurized at the higher value from the first pilot signal line. The roof support and valve 70 move towards the conveyor and when it has advanced to a predetermined distance from the conveyor, the movable valve element of valve 70 is unseated by engagement of a plunger 72 with a nose 73 on the stationary jack rod. This means that the pressure in line 69 rises from the reduced value (from reducing valve 82) to the higher value, and the change in pressure operates the counter.

The operator can also obtain a visual indication that the roof support has advanced to this position by the change in position of the needle of the pressure gauge 74.

Another such monitoring device is a counter 75 combined with an indicator 76. The indicator 76 has a pistonandcylinder device 77 associated with it. One end of the pistonand-cylinder device 77 is connected by a line 78 to the main pressure supply line and the other end of the piston-andcylinder device is connected to the pull-pressure supply line 17. The pull-pressure supply line 17 is also connected to the main pressure supply line by a pressure-operated valve 79.

Normally this valve is held open and the two ends of the piston-and-cylinder device 77 communicate with each other. The net pressure acting on the piston of the device 77 sets the pointer at the right-hand end of the indicator 76.

When the support control valve 25 is moved to its first position, to collapse the props and move the supports towards the conveyor, the pressure rise in the first pilot signal line 27 closes valve 79. In this position valve [4 is opened to allow flow of liquid from line 17 to jack 9. The liquid for this flows from left-hand end of device 77, being ejected therefrom by the pressure on the piston from the main pressure supply line.

The counter 75 operates each time the pointer moves away from it to the left, thus indicating the total number of units which have started to operate.

In the embodiment of the invention just described, when the support control valve 25 was in its second position, to set the props against a roof, the first pilot signal line 27 was pressurized at a value (say 1,000 pounds per square inch) which is lower than that (say 2,000 pounds per square inch) at which it is pressurized when the valve 25 is in its first position. The

reason for pressurizing the line 27 at a lower value is to hold open the valve 14, valve 22 and the sequence valves of those supports which have already operated and through which the first signal must pass in order to actuate further units.

This is not an essential part of this invention because the valves could be held open in other ways.

The valve 28 may be a 2-way, 2-position valve and when in its first position, as mentioned in connection with FIG. 4, the advancing operation will take place from left to right. In this first position a line 83, which is connected to the line, corresponding to line 53, extending from the sequence valves of the last support to operate when the advancing operation takes place from left to right, is also connected to line 84 which, in turn, is connected to main return line 6.

On completion of the sequence, valve 26 is returned to its ofi'" position which removes pressure from lines 27, 29 and 81 so permitting all the sequence valves to return to their original positions.

Thereafter, when it is desired to initiate an advancing operation, which takes place from right to left, valve 26 is moved to its previous position and the valve 28 is moved to its second position. Line 83 is now connected to line 27 and thus the advancing operation can begin from the right-hand end of the coal-face.

It will have been noted that the valves l2, l3, l4, l and 22 have handles associated with them. These handles enable any one of the roof supports to be operated manually, instead of by remote control, if that should become desirable during an advancing sequence.

In a further embodiment of the invention, when the support control valve is in its second position and the second pilot signal line is pressurized, the first pilot signal line may also be pressurized at that value to which it is pressurized when the support control valve is in its first position. In this further embodiment, the second sequence valve of a support will be held in the position shown in the drawings by means of an additional piston exposed to the second pilot pressure and arranged to oppose the action of the piston 51 until the second pilot signal pressure is removed.

In the embodiment described with reference to the drawings, the pressure supply feeding the first pilot signal line was the same as that feeding the props and jacks of the supports. This need not be so, and a different pressure supply could feed the first pilot signal line.

If, in a roof support system in accordance with the invention, a roof support fails to advance its full amount, say because of debris on the floor, it can be reset against the roof, in that position, by suitable movement of the support control valve. Moving the support control valve back to its first position after resetting of the roof support will cause the next roof support to begin its advancing operation.

Thus the advancing sequence of the roof supports can be continued, even though a roof support fails to advance its full amount, with little or no interruption in the advancing sequence. A roof support which has failed to advance its full amount can be dealt with either during the remainder of or at the end of the advancing sequence. The saving in time, by being able to continue the advancing sequence, is particularly valuable if, as may happen, several roof supports in the series fail to advance as they should.

What we claim is:

1. In a multiple roof support system, first and second pilot fluid pressure signal transmission lines, a plurality of roof supports, each of which has a connection with the first pilot fluid pressure signal transmission line, and is responsive to a signal therein of a particular pressure to advance in relation to an anchorage, and each of which has a connection with the second pilot fluid pressure signal transmission line and is responsive to a signal therein of a particular pressure to reset against the roof, first isolating means in the connection between the first pilot fluid pressure signal transmission line and each support after the first to be operated, to isolate each such support from the signal therein, second isolating means in the connection between the second pilot fluid pressure signal transmission line and each support, to isolate each support from the signal therein, signal generation means including a fluid pressure source, a two-position movable fluid flow control valve member which in the respective positions thereof, alternately interconnects the first and second pilot fluid pressure signal transmission lines with the fluid pressure source, to generate separate signals in the lines, first deactuating means responsive to the advance of each support when the first pilot signal transmission line is interconnected with the fluid pressure source, to deactuate the second isolating means in the connection between the respective support and the second pilot signal transmission line, and second deactuating means responsive to.the resetting of each support when the second pilot signal transmission line is interconnected with the fluid pressure source, to deactuate the first isolating means in the connection between the first pilot signal transmission line and the next succeeding support in the sequence of operation.

2. The multiple roof support system according to claim 1 wherein the first deactuating means is responsive to pressurization of the first pilot signal transmission line, to deactuate the second isolating means, and there are means operative to maintain a pressure of less than the aforesaid signal in the first pilot signal transmission line during the resetting of each support, to maintain the deactuated condition of the second isolating means.

3. The multiple roof support system according to claim 1 wherein the second deactuating means has a connection with and is responsive to a signal of a particular pressure in the second pilot signal transmission line, to deactuate the first isolating means, and there are means operative to maintain a pressure of less than the latter signal in the latter connection between the second deactuating means and the second pilot signal transmission line until the respective support has reset, to maintain the isolated condition of the next succeeding support.

4. The multiple roof support system according to claim 1 wherein each of the first and second isolating means includes a valve member and each of the first and second deactuating means includes a piston member which is responsive to the signal in the first and second pilot signal transmission lines, respectively, to open the valve members of the second and first isolating means, respectively, when the respective supports have advanced and reset respectively.

5. The multiple roof support system according to claim 1 wherein the anchorage is advanceable in relation to certain of the supports, and there are means responsive to the signal in the first pilot signal transmission line when a support is advanced in relation to the anchorage, to advance the anchorage in relation to a relatively succeeding support among the aforesaid certain supports.

6. The multiple roof support system according to claim 1 further comprising normally closed valve means in the connection between the first pilot signal transmission line and each support after the first to be operated, which are responsive to the signal in the first pilot signal transmission line to interconnect the line sequentially with each such support.

7. The multiple roof support system according to claim 1 further comprising third isolating means operable to isolate each support from the signals generated for succeeding supports, after it has undergone an advancing operation and is reset against the roof.

8. The multiple roof support system according to claim 7 wherein the first and third isolating means in conjunction with each pair of successively operated supports, includes a valve member which is operable to interconnect the first support to be operated in the aforesaid pair of supports, with the first pilot signal transmission line, while isolating the second support to be operated in the pair of supports, from the signal generated for the aforesaid first support, but operable when deactuated by the second deactuating means, to interconnect the second support of the pair with the first pilot signal transmission line, while isolating the first support of the pair from the signal to be generated for the second support of the pair.

number of supports and interconnecting the first pilot signal transmission line with the next succeeding support in the sequence after the aforesaid given number thereof, and normally closed valve means in the connection between the third pilot signal transmission line and the latter said next successive support, responsive to the signal in the first pilot signal transmission line to open the third pilot signal transmission line to the aforesaid next successive support when the given number of supports has been reset. 

1. In a multiple roof support system, first and second pilot fluid pressure signal transmission lines, a plurality of roof supports, each of which has a connection with the first pilot fluid pressure signal transmission line, and is responsive to a signal therein of a particular pressure to advance in relation to an anchorage, and each of which has a connection with the second pilot fluid pressure signal transmission line and is responsive to a signal therein of a particular pressure to reset against the roof, first isolating means in the connection between the first pilot fluid pressure signal transmission line and each support after the first to be operated, to isolate each such support from the signal therein, second isolating means in the connection between the second pilot fluid pressure signal transmission line and each support, to isolate each support from the signal therein, signal generation means including a fluid pressure source, a two-position movable fluid flow control valve member which in the respective positions thereof, alternately interconnects the first and second pilot fluid pressure signal transmission lines with the fluid pressure source, to generate separate signals in the lines, first deactuating means responsive to the advance of each support when the first pilot signal transmission line is interconnected with the fluid pressure source, to deactuate the second isolating means in the connection between the respective support and the second pilot signal transmission line, and second deactuating means responsive to the resetting of each support when the second pilot signal transmission line is interconnected with the fluid pressure source, to deactuate the first isolating means in the connection between the first pilot signal transmission line and the next succeeding support in the sequence of operation.
 2. The mulTiple roof support system according to claim 1 wherein the first deactuating means is responsive to pressurization of the first pilot signal transmission line, to deactuate the second isolating means, and there are means operative to maintain a pressure of less than the aforesaid signal in the first pilot signal transmission line during the resetting of each support, to maintain the deactuated condition of the second isolating means.
 3. The multiple roof support system according to claim 1 wherein the second deactuating means has a connection with and is responsive to a signal of a particular pressure in the second pilot signal transmission line, to deactuate the first isolating means, and there are means operative to maintain a pressure of less than the latter signal in the latter connection between the second deactuating means and the second pilot signal transmission line until the respective support has reset, to maintain the isolated condition of the next succeeding support.
 4. The multiple roof support system according to claim 1 wherein each of the first and second isolating means includes a valve member and each of the first and second deactuating means includes a piston member which is responsive to the signal in the first and second pilot signal transmission lines, respectively, to open the valve members of the second and first isolating means, respectively, when the respective supports have advanced and reset respectively.
 5. The multiple roof support system according to claim 1 wherein the anchorage is advanceable in relation to certain of the supports, and there are means responsive to the signal in the first pilot signal transmission line when a support is advanced in relation to the anchorage, to advance the anchorage in relation to a relatively succeeding support among the aforesaid certain supports.
 6. The multiple roof support system according to claim 1 further comprising normally closed valve means in the connection between the first pilot signal transmission line and each support after the first to be operated, which are responsive to the signal in the first pilot signal transmission line to interconnect the line sequentially with each such support.
 7. The multiple roof support system according to claim 1 further comprising third isolating means operable to isolate each support from the signals generated for succeeding supports, after it has undergone an advancing operation and is reset against the roof.
 8. The multiple roof support system according to claim 7 wherein the first and third isolating means in conjunction with each pair of successively operated supports, includes a valve member which is operable to interconnect the first support to be operated in the aforesaid pair of supports, with the first pilot signal transmission line, while isolating the second support to be operated in the pair of supports, from the signal generated for the aforesaid first support, but operable when deactuated by the second deactuating means, to interconnect the second support of the pair with the first pilot signal transmission line, while isolating the first support of the pair from the signal to be generated for the second support of the pair.
 9. The multiple roof support system according to claim 1 further comprising regeneration means responsive to the resetting of a given number of supports, to bypass the signal in the first pilot signal transmission line around the said given number of supports, to assure that the next succeeding support in the sequence of operation is subjected to the signal, notwithstanding pressure losses in the system theretofore.
 10. The multiple roof support system according to claim 9 wherein the regeneration means includes a third pilot signal transmission line bypassing around the aforesaid given number of supports and interconnecting the first pilot signal transmission line with the next succeeding support in the sequence after the aforesaid given number thereof, and normally closed valve means in the connection between the third pilot signal transmission line and the latter said next successive support, responsive to the signal in the first pilot signal transmission line to open the third pilot signal transmission line to the aforesaid next successive support when the given number of supports has been reset. 